Use `^` version for react-native preset

Summary:See https://github.com/facebook/react-native/issues/6798
Closes https://github.com/facebook/react-native/pull/6814

Differential Revision: D3138776

fb-gh-sync-id: f43404e7bfdf0e3e7c6df16681653d1dd4016e1a
fbshipit-source-id: f43404e7bfdf0e3e7c6df16681653d1dd4016e1a

package.json

@@ -134,7 +134,7 @@
     "babel-core": "^6.6.4",
     "babel-plugin-external-helpers": "^6.5.0",
     "babel-polyfill": "^6.6.1",
-    "babel-preset-react-native": "1.5.2",
+    "babel-preset-react-native": "^1.5.2",
     "babel-register": "^6.6.0",
     "babel-types": "^6.6.4",
     "babylon": "^6.6.4",